How to get round "salient" shape of building
In whichever space is specified, the Simple Deform > Bend modifier progressively rotates elements about Z, by a factor of the element's X distance from the origin.

(The X distance is normalized, so there is 0 rotation at X=0, and min_X -> max_X is mapped onto the total angle of bend)

The direction of rotation is determined by Y of the specified space. The 'inside' of the bend is in positive Y.

By default, the modifier's space is set by the pivot of the modified object, but you can set the origin and orientation of the modifier to the pivot of any other object by allocating it as 'Axis, Origin' in the modifier. (Usually using an empty)

This object was created with its ridges up in world Z, its length down X.


The object bent around its own pivot, aligned to world





Using an Empty as the modifier's origin, with its local Y rotated to world positive Z  





Using an Empty as the modifier's origin, with its local Y rotated to world negative Z